Weight gain

Sorry for the ramble

I am driving myself crazy. My dr has told me that if my bmi hits 50 then I can't have my baby at our hospital and would have to travel 5 hours away. My bmi is currently 45.2 (ish). I am currently around 250 lbs (280 would be 50bmi) I have lost 40lbs since the start of my pregnancy and my dr keeps telling me it would be good to keep losing weight. I have been watching my calories and have been eating around 1700/day but I am hungry all the time now. I will be 28 weeks tomorrow and I have no idea how much I should be eating and all my dr and ob say is keep eating healthy and try and lose weight. It is driving me crazy. I just want a giant bowl of pasta lol